Oskari Heikinheimo discusses fertility counseling and pregnancy outcomes in endometriosis

Individuals with surgically verified endometriosis face significantly higher risks of early pregnancy complications, including miscarriage and ectopic pregnancy, compared to those without the condition. A large registry-based cohort study, published in the American Journal of Obstetrics & Gynecology in January 2026, followed 10,105 individuals in Finland with a first surgical diagnosis of endometriosis and compared them with 19,526 age- and residence-matched controls.

The study utilized national registries to capture all pregnancies from age 15 through the end of follow-up, yielding more than 256,000 person-years in the endometriosis cohort. Among pregnancies with known outcomes, births were less common in the endometriosis group at 72.0%, compared to 75.7% in the control group. Conversely, miscarriage rates were 15.6% vs 10.4%, and ectopic pregnancy occurred in 3.5% of the endometriosis cohort compared to 1.5% of controls. After adjustment, endometriosis was associated with a 51% higher risk of miscarriage and a more than 2-fold increased risk of ectopic pregnancy.

Oskari Heikinheimo, Department of Obstetrics and Gynecology, Helsinki University Hospital and University of Helsinki, noted that the data also revealed fewer induced abortions among those with endometriosis. “Our interpretation is that maybe that's a reflection of overall reduced fertility in women with endometriosis, also at the population level,” Heikinheimo said. “But obviously, since we are using oral contraceptives quite a bit for endometriosis symptom management…then the use of effective contraception reduces the need [for] induced abortion.”

The study found an adjusted incidence rate ratio of 0.87 for lifetime pregnancy, indicating reduced fertility in the endometriosis cohort. Heikinheimo emphasized that these findings should inform how clinicians approach family planning with their patients, particularly as many individuals delay childbearing.

“If there is a suspicion of endometriosis, bring the issue of reduced fertility in women with endometriosis into discussion,” Heikinheimo said. “The postponing of fertility is an increasing challenge. Developing a sort of patient-friendly way of increasing awareness is important.”

While the results do not mandate routine screening for early complications, they underscore the necessity of awareness in clinical counseling. Heikinheimo noted that informing patients of the increased risk of ectopic pregnancy and miscarriage is not meant to cause alarm, but rather to allow for more proactive reproductive support and timely diagnosis.

Reference

Gurney JM, Tuominen A, Saavalainen J, et al. Endometriosis and early pregnancy outcomes: a registry-based cohort study in Finland. Am J Obstet Gynecol. Preprint posted online February 2026. doi:10.1016/j.ajog.2026.01.027